Resistor having a resistor element comprising resistance alloy with improved properties

ABSTRACT

The invention relates to a resistor alloy ( 3 ) for an electrical resistor, in particular for a low-resistance current-measuring resistor, having a copper constituent, a manganese constituent and a nickel constituent. According to the invention, the manganese constituent has a mass fraction of 23% to 28%, while the nickel constituent has a mass fraction of 9% to 13%. The mass fractions of the alloy constituents are adjusted to one another in such a manner that, compared to copper, the resistor alloy ( 3 ) has a low thermal electromotive force at 20° C. of less than ±1μν/K. The invention furthermore includes a component made from such a resistor alloy and a production method therefor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 14/891,133, which was filed Nov. 13, 2015 as a U.S. national phase of PCT/EP2014/001669, filed Jun. 18, 2014, which claims priority to DE 10 2013 010 301.0, filed Jun. 19, 2013, the contents of which applications are incorporated herein by reference in their entireties for all purposes.

BACKGROUND OF THE INVENTION

The invention relates to a resistance alloy for an electrical resistor, in particular for a low-ohm current-measuring resistor. The invention further includes a component produced therefrom and a corresponding production method.

Copper-manganese-nickel alloys have already been in use for a long time as materials for precision resistors, in particular for low-ohm current-measuring resistors (“shunts”). An example of such a copper-manganese-nickel alloy is the resistance alloy marketed by the applicant under the trade name Manganin® (e.g. Cu₈₄Ni₄Mn₁₂) with a mass fraction of copper of 82-84%, a mass fraction of nickel of 2-4% and a mass fraction of manganese of 12-15%. The known copper-manganese-nickel alloys satisfy all requirements for resistance alloys for precision resistors, such as, for example, a low temperature coefficient of the specific electrical resistance, a low thermal electromotive force against copper and a high stability of the electrical resistance over time. In addition, the known copper-manganese-nickel alloys have good technological properties, in particular good working properties, allowing such copper-manganese-nickel alloys to be worked to form wires, ribbons, foils and resistor components. A disadvantage of the known copper-manganese-nickel alloys is, however, the limitation to relatively low specific electrical resistances of not more than 0.5 (Ω·mm²)/m.

For higher specific electrical resistances, nickel-chromium alloys, for example, are known, but these likewise exhibit various disadvantages. On the one hand, nickel-chromium alloys are mostly substantially more expensive than copper-manganese-nickel alloys. On the other hand, nickel-chromium alloys are more difficult to handle in many respects from the production point of view. For example, the hot workability of nickel-chromium alloys is relatively poor, and complex heat treatment processes are necessary in order to establish specific electro-physical material properties. In addition, the working temperatures in the melting process are about 500K higher in the case of nickel-chromium alloys than in the case of copper-manganese-nickel alloys, which leads to higher energy costs and material wear of the working equipment. Moreover, the good acid resistance of nickel-chromium alloys, which is otherwise desirable, gives rise to major problems in the production of resistor structures by etching and makes the removal by pickling of oxides caused by heat treatment a complex and non-hazardous manufacturing step.

Also known is the copper-manganese-nickel-aluminum alloy 29-5-1, which has a specific electrical resistance of 1 (Ω·mm²)/m and thereby satisfies the requirement for a low temperature coefficient of the specific electrical resistance. However, this resistance alloy has a high thermal electromotive force against copper at 20° C. of +3 μV/K, resulting in high fault currents which render this alloy unsuitable for precise measurement applications.

In relation to the prior art, reference is further to be made to DE 1 092 218 B, U.S. Pat. No. 3,985,589, JP 62202038 A and EP 1 264 906 A1.

Finally, DE 1 033 423 B discloses a resistance alloy of the generic type. However, this known resistance alloy has the disadvantage of a relatively high, in terms of amount, thermal electromotive force against copper of −2 μV/K.

Accordingly, the object underlying the invention is to provide a correspondingly improved resistance alloy based on copper-manganese-nickel, which resistance alloy has as high a specific electrical resistance as possible, a low thermal electromotive force against copper, a low temperature coefficient of the electrical resistance, and a high stability of the specific electrical resistance over time, and which combines these properties with the good technological properties (e.g. workability) described at the beginning of the known copper-manganese-nickel alloys.

This object is achieved by a resistance alloy according to the invention.

SUMMARY OF THE INVENTION

The resistance alloy according to the invention firstly has, in conformity with the known copper-manganese-nickel alloys mentioned at the beginning, a copper constituent, a manganese constituent and a nickel constituent. The invention is distinguished by the fact that the manganese constituent has a mass fraction of from 23% to 28%, while the nickel constituent has a mass fraction of from 9% to 13%. It has been shown in practice that such a resistance alloy based on copper-manganese-nickel satisfies the requirements described above.

The mass fractions of the various alloying constituents are so matched to one another that the resistance alloy according to the invention has a low thermal electromotive force against copper which at 20° C. is less than ±1 μV/K, ±0.5 μV/K or even less than ±0.3 μV/K.

The mass fraction of the manganese constituent can be, for example, in the range of 24%-27%, 25%-26%, 23%-25%, 23%-26%, 23%-27%, 24%-28%, 25%-28%, 26%-28% or 27%-28%. A mass fraction of the manganese constituent of 24.5%-25.5% is particularly advantageous.

The mass fraction of the nickel constituent, on the other hand, can be, for example, in the range of 9%-12%, 9%-11%, 9%-10%, 10%-13%, 11%-13%, 12%-13%, 10%-12% or 11%-12%.

Moreover, it has been shown that an additional tin constituent with a mass fraction of up to 3% can contribute towards improving the temperature stability of the specific electrical resistance. The resistance alloy according to the invention therefore preferably also has a tin constituent with a mass fraction of up to 3%.

Furthermore, it has been shown in practice that an additional silicon constituent with a mass fraction of up to 1% likewise contributes towards improving the temperature stability of the specific electrical resistance. The resistance alloy according to the invention can therefore have, in addition to the tin constituent or instead of the tin constituent, a silicon constituent with a mass fraction of up to 1%.

It has further been shown in practice that an additional magnesium constituent with a mass fraction of up to 0.3% contributes towards avoiding embrittlement as a result of precipitation hardening effects. The resistance alloy according to the invention can therefore also have, in addition to the tin constituent and/or the silicon constituent or instead of those constituents, a magnesium constituent with a mass fraction of up to 0.3%.

A preferred embodiment of a resistance alloy according to the invention is Cu₆₅Ni₁₀Mn₂₅ with a mass fraction of copper of 65%, a mass fraction of nickel of 10% and a mass fraction of manganese of 25%.

Another embodiment of a resistance alloy according to the invention is Cu₆₄Ni₁₀Mn₂₅Sn₁ with a mass fraction of copper of 64%, a mass fraction of nickel of 10%, a mass fraction of manganese of 25% and a mass fraction of tin of 1%. The mass fraction of tin can, however, also be smaller, which is then balanced by a correspondingly higher mass fraction of copper.

A further embodiment of a resistance alloy according to the invention is Cu₆₂Ni₁₁Mn₂₇ with a mass fraction of copper of 62%, a mass fraction of nickel of 11% and a mass fraction of manganese of 27%.

A further embodiment of a resistance alloy according to the invention is Cu₆₁Ni₁₁Mn₂₇Sn₁ with a mass fraction of copper of 61%, a mass fraction of manganese of 27%, a mass fraction of nickel of 11% and a mass fraction of tin of 1%. The mass fraction of tin can also be smaller, which is balanced by a correspondingly higher mass fraction of copper.

In the resistance alloy according to the invention, the specific electrical resistance is preferably in the range of from 0.5 (Ω·mm²)/m to 2 (Ω·mm²)/m.

Furthermore, the specific electrical resistance of the resistance alloy according to the invention preferably has a high stability over time with a relative change of less than ±0.5% or ±0.25%, in particular within a period of 3000 hours and at a temperature of at least ±140° C., the higher temperature of at least ±140° C. accelerating the ageing process.

In addition, it is to be mentioned that the resistance alloy according to the invention preferably has a low thermal electromotive force against copper, which at 20° C. is preferably less than ±1 μV/K, ±0.5 μV/K or even less than ±0.3 μV/K.

Furthermore, the specific electrical resistance is relatively temperature-constant with a low temperature coefficient of preferably less than ±50·10⁻⁶ K⁻¹, +35·10⁻⁶ K⁻¹, ±30·10⁻⁶ K⁻¹ or ±20·10⁻⁶ K⁻¹, in particular in a temperature range of from +20° C. to +60° C.

With regard to the electrical properties of the resistance alloy according to the invention, it is further to be mentioned that the resistance alloy has a resistance/temperature curve, which shows the relative change in resistance in dependence on the temperature, the resistance/temperature curve having a second zero-crossing which preferably occurs at a temperature of more than +20° C., +30° C. or +40° C. and/or at a temperature of less than +110° C., +100° C. or +90° C.

With regard to the mechanical properties of the resistance alloy according to the invention, mention is to be made of a mechanical tensile strength of at least 500 MPa, 550 MPa or 580 MPa.

In addition, the resistance alloy according to the invention preferably has a yield strength of at least 150 MPa, 200 MPa or 260 MPa, while the breaking elongation is preferably greater than 30%, 35%, 40% or even 45%.

With regard to the technological properties of the resistance alloy according to the invention, it is to be mentioned that the resistance alloy is preferably capable of being soft-soldered and/or hard-soldered.

In addition, the resistance alloy according to the invention is preferably very readily workable, which manifests itself in the case of wire drawing in a logarithmic deformation degree of at least φ=−4.6.

The resistance alloy according to the invention can be produced in various forms of delivery, such as, for example, in the form of a wire (e.g. round wire, flat wire), in the form of a ribbon, in the form of a sheet, in the form of a rod, in the form of a tube or in the form of a foil. However, the invention is not limited in respect of the forms of delivery to the forms of delivery mentioned above.

The invention additionally also includes an electrical or electronic component having a resistor element made from the resistance alloy according to the invention. For example, it can be a resistor, in particular a low-ohm current-measuring resistor, as is known per se from EP 0 605 800 A1, for example.

Finally, the invention also includes a corresponding production method, as already follows from the above description of the resistance alloy according to the invention.

Within the scope of the production method according to the invention, the resistance alloy can be subjected to an artificial thermal ageing process, wherein the resistance alloy is heated from a starting temperature to an ageing temperature. This process can be repeated several times within the scope of the ageing process, the resistance alloy repeatedly being periodically heated to the ageing temperature and cooled to the starting temperature again. The ageing temperature can be, for example, in the range of from +80° C. to +300° C., while the starting temperature is preferably less than +30° C. or +20° C.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

Other advantageous further developments of the invention will be explained in greater detail hereinbelow with reference to the figures, together with the description of the preferred embodiments of the invention. In the figures:

FIG. 1: is a phase diagram for a copper-manganese-nickel alloy, the region according to the invention being plotted in the phase diagram,

FIG. 2: shows an example of a construction of a current-measuring resistor according to the invention having a resistor element made from the resistance alloy according to the invention,

FIG. 3: is a diagram illustrating the temperature dependence of the specific electrical resistance in the case of different embodiments of the resistance alloy according to the invention, and

FIG. 4: is a diagram illustrating the long-term stability of the resistance alloy according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a phase diagram of a copper-manganese-nickel alloy, the mass fraction of copper being shown on the top left axis, while the mass fraction of nickel is shown on the top right axis. The mass fraction of manganese, on the other hand, is shown on the bottom axis.

On the one hand, the phase diagram shows in hatched form a zone 1 in which the resistance alloy tends to precipitation hardening.

On the other hand, the phase diagram shows a line 2 which is designated α=0, the temperature coefficient of the resistance alloy on this line being equal to zero, that is to say the resistance alloy has on this line a specific electrical resistance which is independent of the temperature.

Finally, the phase diagram also shows a region 3 which characterizes the resistance alloy according to the invention, the mass fraction of manganese in the region 3 being from 23% to 28%, while the mass fraction of nickel in the region 3 is from 9% to 13%.

FIG. 2 shows a simplified perspective view of a current-measuring resistor 4 according to the invention, as is already known per se from EP 0 605 800 A1 so that, in order to avoid repetition, reference is made to that patent application, the content of which is to be incorporated in its entirety in the present description.

The current-measuring resistor 4 consists substantially of two plate-like connecting parts 5, 6 of copper and, arranged therebetween, a resistor element 7 made from the resistance alloy according to the invention, which alloy can be, for example, Cu₆₅Ni₁₀Mn₂₅.

FIG. 3 shows the temperature-dependent development of the relative resistance change DR/R20 in dependence on the temperature. It is also apparent therefrom that the various exemplary resistance alloys each have a second zero-crossing 8, 9 or 10, the zero-crossing 8 occurring approximately at a temperature T_(ZERO1)=43° C., while the zero-crossing 9 occurs approximately at a temperature T_(ZERO2)=75° C. The zero-crossing 10, on the other hand, occurs approximately at a temperature of T_(ZERO3)=82° C.

Finally, FIG. 4 shows the long-term stability of the resistance alloy according to the invention. It is apparent therefrom that the relative resistance change dR over a period of 3000 hours is substantially less than 0.25%.

The invention is not limited to the preferred embodiments described above. Rather, a plurality of variants and modifications are possible which likewise make use of the inventive concept and therefore fall within the scope of protection. Moreover, the invention also claims protection for the subject-matter and features of the dependent claims independently of the claims on which they are dependent, that is to say, for example, also without the characterizing feature of the main claim.

LIST OF REFERENCE NUMERALS

-   1 Zone of precipitation hardening -   2 Line with α=0 (temperature stability) -   3 Alloying region according to the invention -   4 Current-measuring resistor -   5 Connecting part -   6 Connecting part -   7 Resistor element -   8 Second zero-crossing -   9 Second zero-crossing -   10 Second zero-crossing 

What is claimed is:
 1. A resistor comprising a resistor element, wherein the resistor element comprises a resistance alloy comprising: a) a copper constituent, b) a manganese constituent, c) a nickel constituent, d) a tin constituent for improving a temperature stability of a specific electrical resistance of the resistance alloy, wherein mass fractions of the manganese constituent and of the nickel constituent are effective to provide the resistance alloy with a low thermal electromotive force against copper at 20° C. of less than +1 μV/K and more than −1 μV/K, a mass fraction of the nickel constituent is 9%-13%, a mass fraction of the manganese constituent is 23%-28%, a mass fraction of the tin constituent is up to 1% and a mass fraction of the copper constituent is 58%-68%.
 2. The resistor according to claim 1, wherein the resistor element is arranged between two plate-like connecting parts comprising copper.
 3. The resistor according to claim 1, wherein the resistance alloy further comprises a silicon constituent with a mass fraction of up to 1% for improving a temperature stability of a specific electrical resistance of the resistance alloy.
 4. The resistor according to claim 1, wherein the resistance alloy further comprises a magnesium constituent with a mass fraction of up to 0.3% for avoiding embrittlement as a result of precipitation hardening effects.
 5. The resistor according to claim 1, wherein the resistance alloy has a specific electrical resistance which is greater than 0.5 (Ω·mm²)/m and less than 2.0 (Ω·mm²)/m.
 6. The resistor according to claim 1, wherein the resistance alloy has a specific electrical resistance having a high stability over time with a relative change of less than ±0.5% within a period of 3000 hours.
 7. The resistor according to claim 1, wherein the low thermal electromotive force against copper at 20° C. possessed by the resistance alloy is less than +0.5 μV/K and more than −0.5 μV/K.
 8. The resistor according to claim 1, wherein the resistance alloy has a specific electrical resistance having a low temperature coefficient of less than +50·10⁻⁶ K⁻¹ and more than −50·10⁻⁶ K⁻¹ in a temperature range of from +20° C. to +60° C.
 9. The resistor according to claim 1, wherein the resistance alloy has a resistance/temperature curve which shows relative resistance change in dependence on temperature, the resistance/temperature curve having a second zero-crossing which occurs at a temperature of more than +20° C. and at less than +110° C.
 10. The resistor according to claim 1, wherein the resistance alloy has: a) a mechanical tensile strength of at least 500 MPa, and b) a yield strength of at least 150 MPa, and c) a breaking elongation of at least 30%.
 11. The resistor according to claim 1, wherein the resistor element is a wire, a ribbon, a sheet, a rod, a tube or a foil.
 12. The resistor according to claim 3, wherein the resistance alloy further comprises a magnesium constituent with a mass fraction of up to 0.3% for avoiding embrittlement as a result of precipitation hardening effects.
 13. The resistor according to claim 12, wherein the resistance alloy has a specific electrical resistance which is greater than 0.5 (Ω·mm²)/m and less than 2.0 (Ω·mm²)/m.
 14. The resistor according to claim 13, wherein the resistance alloy has a specific electrical resistance having a high stability over time with a relative change of less than ±0.5% within a period of 3000 hours.
 15. The resistor according to claim 14, wherein the low thermal electromotive force against copper at 20° C. possessed by the resistance alloy is less than +0.5 μV/K and more than −0.5 μV/K.
 16. The resistor according to claim 15, wherein the resistance alloy has a specific electrical resistance having a low temperature coefficient of less than +50·10⁻⁶ K⁻¹ and more than −50·10⁻⁶ K⁻¹ in a temperature range of from +20° C. to +60° C.
 17. The resistor according to claim 16, wherein the resistance alloy has a resistance/temperature curve which shows relative resistance change in dependence on temperature, the resistance/temperature curve having a second zero-crossing which occurs at a temperature of more than +20° C. and at less than +110° C.
 18. The resistor according to claim 17, wherein the resistance alloy has: a) a mechanical tensile strength of at least 500 MPa, and b) a yield strength of at least 150 MPa, and c) a breaking elongation of at least 30%.
 19. The resistor according to claim 18, wherein the resistor element is a wire, a ribbon, a sheet, a rod, a tube or a foil.
 20. The resistor according to claim 19, wherein the resistor element is arranged between two plate-like connecting parts comprising copper. 